Apparatus and method for detecting an image

ABSTRACT

In order to detect an image generated by an image source, a mirror arrangement is arranged between the image source and a detector. The mirror arrangement includes two spaced-apart deflection mirrors, which are parallel to each other or form an acute angle of less than 90° between them. In particular when the image source is a scintillator layer, shielding of X-rays from the detector with simultaneous compact dimensioning of the apparatus is achieved in this manner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from German Patent Application No.102008007595.7-51, which was filed on Feb. 6, 2008, and fromInternational Patent Application No. PCT/EP2009/000669, which was filedon Feb. 2, 2009, which are both incorporated herein in their entirety byreference.

The present invention relates to image detection and, in particular, toimage detection of scintillator screens.

BACKGROUND OF THE INVENTION

Optical pickup of a planar image source, for example a screen, which maybe implemented as a scintillator screen, may be performed using one ormore cameras. Such a pickup of a screen is achieved, for example, by anX-ray camera which may be employed in digital radioscopy, for examplefor product quality control.

In medical radioscopy, so-called flat-panel detectors are currentlyused. In such flat-panel detectors, X-radiation is typically convertedto visible light via a scintillator screen, and said visible light isthen identified via a semiconductor layer arranged directly behind thescintillator screen in the beam direction and usually consisting ofamorphous silicon, and is converted to an image. The efficiency of ascintillator screen depends, among other things, on the adjusted energyof the X-ray quanta. The higher the energy of the X-radiation, the fewerX-ray quanta will be absorbed in the scintillator and will contribute tothe image. The non-absorbed X-ray quanta may be absorbed by theunderlying semiconductor layer, thereby damaging same. Given anappropriate dose, this radiation damage will eventually cause thedetector to fail.

The field of medicine also uses detectors wherein the X-radiation isinitially converted to visible light by a scintillator, too. However,said visible light is subsequently imaged in an optical manner, e.g.onto CCD cameras.

German patent DE 10301941 B4 shows a camera for optically picking up ascreen, the screen comprising an area, and a predetermined overallresolution being envisaged for the optical pickup, comprising a camerasupport having an array of camera mounts, an array of individual opticalcameras, each individual optical camera being fixedly attached to anassociated camera mount, an individual optical camera comprising a lightsensor and an optics imaging means, the light sensor and the opticsimaging means being operative to pick up a subarea of the screen area atan individual resolution higher than the overall resolution, andcomprising an image processing means for processing individual digitalimages of the array of individual optical cameras so as to generate theoptical pickup of the screen at a predetermined overall resolution, theimage processing means being operative to subject the individual digitalimages to a correction so as to reduce alignment inaccuracies and/orparameter variations in the array of individual optical cameras, acorrection specification being used, for the correction, which isintended for an individual image with a calibration, and the correctiontaking place at a correction resolution which is higher than thepredetermined overall resolution and is lower than or equal to theindividual resolution so as to obtain corrected individual images or acorrected overall image, and to combine adjacent pixels of the correctedindividual images and to then compose the images, or to combine adjacentpixels of the corrected overall image in order to obtain the opticalpickup having the predetermined overall resolution.

EP 0862748 A1 describes an arrangement wherein the visible lightemanating from a scintillator is laterally deflected via a V-shapedmirror arrangement. This lateral deflection results in that the opticallight path behind the mirror is essentially parallel to the scintillatorscreen. Because of this, radiation-sensitive cameras may be arrangedoutside the X-ray path, and radiation damage may be avoided at the sametime. Such an arrangement is shown in FIG. 6, for example. Inparticular, there is a scintillator 600, opposite which the V-shapedmirror arrangement 602 is arranged. The mirror arrangement 602 deflectsthe light received by the scintillator 600. Two sensors 604, 606 arelocated within the light path of the deflected radiation, the sensor 604imaging a first subregion 600 a, whereas the second sensor 606 images asecond subregion 600 b of the scintillator screen. The lateralarrangement of the sensors 604, 606 additionally enables reducedstructural height of the arrangement, so that this arrangement may beintegrated into conventional film cartridges.

A further alternative to the arrangement shown in FIG. 6 is depicted inFIG. 5. Here, only a single mirror 603 is arranged, which images theentire scintillator 600 on a single sensor camera 605. In this case,too, the sensor 605 is arranged laterally in relation to thescintillator.

What is disadvantageous about the concept depicted in FIGS. 5 and 6 isthat the structural height perpendicular to the scintillator screen isreduced since the sensors are arranged laterally. But the lateralarrangement of the sensors has the disadvantage, in turn, that thelateral dimension of the X-ray camera increases considerably. Forexample, in the concept shown in FIG. 6 the structural size of the X-raycamera is no longer determined by the scintillator screen 600, but bythe space that may be taken up by the two sensor cameras 604, 606 and bythe minimum distance of the two sensor cameras 604, 606 from theV-shaped mirror 602 so that the optical imaging conditions are achieved.As compared to the implementation wherein the semiconductor layer isarranged directly behind the scintillator screen, the length of theX-ray camera therefore increases considerably.

SUMMARY

According to an embodiment, an apparatus for detecting an image mayhave: an image source including a scintillator layer which is excitableby an X-radiation for emitting the radiation; a mirror arrangement fordeflecting radiation which may be generated by the image source; and adetector for receiving radiation deflected by the mirror arrangement,the detector being arranged within a light path of the X-radiation, themirror arrangement including: a first mirror arranged to reflect theradiation generated by the image source; a second mirror arranged toreflect radiation reflected by the first mirror, the first mirror andthe second mirror being spaced apart from one another and being parallelto one another or forming an angle of less than 90° between them, andthe mirror arrangement being configured to shield at least someX-radiation which penetrates the scintillator layer from the detectorsuch that X-radiation which passes through the scintillator layer cannotarrive directly at the detector, but passes through the first mirror andthe second mirror and is at least weakened in the process, such that thedetector is protected from X-radiation by the mirror arrangement.

According to another embodiment, a method of detecting an image may havethe steps of: emitting a radiation which represents an image; deflectingthe radiation so as to acquire deflected radiation; and detecting thedeflected radiation so as to acquire the image, during deflecting, theradiation being reflected by a first mirror, and the radiation reflectedby the first mirror being deflected by a second mirror, the first mirrorand the second mirror being spaced apart from each other and beingparallel to each other or forming an angle of less than 90° betweenthem, during emitting, a scintillator layer being excited by X-radiationso as to generate the emitted radiation, and during deflecting,shielding of the X-radiation from the detector being conducted such thatX-radiation passing through the scintillator layer cannot arrive at thedetector directly, but passes through the first mirror and the secondmirror and is at least weakened in the process, such that the detectoris protected from X-radiation by the mirror arrangement.

According to another embodiment, a method of manufacturing an apparatusincluding an image source including a scintillator layer which isexcitable by an X-radiation for emitting the radiation, a mirrorarrangement for deflecting radiation which may be generated by the imagesource, and a detector for receiving radiation deflected by the mirrorarrangement, the detector being arranged within a light path of theX-radiation, may have the steps of: arranging a first mirror to reflectradiation emitted by the image source; and arranging a second mirror toreflect radiation reflected by the first mirror, and during arrangingthe first mirror and the second mirror, the two mirrors being arrangedsuch that they are spaced apart from each other and are parallel to eachother or form an angle of less than 90° between them, and the mirrorarrangement being configured to shield at least some X-radiation whichpenetrates the scintillator layer from the detector such thatX-radiation which passes through the scintillator layer cannot arrivedirectly at the detector, but passes through the first mirror and thesecond mirror and is at least weakened in the process, such that thedetector is protected from X-radiation by the mirror arrangement.

The apparatus for detecting an image comprises an image source, a mirrorarrangement for deflecting radiation which may be generated by the imagesource, and a detector for picking up radiation deflected by the mirrorarrangement, the mirror arrangement comprising a first mirror arrangedto reflect the radiation generated by the image source, and a secondmirror arranged to reflect radiation reflected by the first mirror, thefirst and second mirrors being spaced apart from each other and beingparallel to each other or forming an angle smaller than 90°.

In particular when the image source is planar and is implemented as ascintillator, and when the apparatus for detecting is implemented as anX-ray camera, two dimensions, i.e. the length and width, of the outersize of the X-ray camera will roughly correspond to the length and widthof the scintillator in order to achieve a compact implementation.However, the depth will be determined by the mirror arrangement and thedetector. With regard to its length and width, the scintillatorrepresents an essential element of a pickup device. If the scintillatoris larger, i.e. longer and/or wider, a larger camera will also beaccepted. If the scintillator becomes smaller, however, i.e. narrowerand shorter, the size of the camera should also decrease. In order toachieve that the size of the camera is determined, with regard to twodimensions, essentially by the size of the scintillator screen withregard to the two dimensions, the detector is arranged, in accordancewith the present invention, opposite an image source and advantageouslyeven within the light path of the image source.

However, to provide decoupling of the detector from the image source forthe event that the image source is a scintillator and that X-rays existwhich are detrimental to the detector, a mirror arrangement is placedbetween the detector and the image source, said mirror arrangement beingconfigured to deflect any radiation output by the image source, and toproject it onto the detector.

Preferably the image source is a planar image source which in oneembodiment may have a flat or curved (e.g. cylindrical) area emittingthe radiation to be detected. By way of example only, the image sourceis described as a scintillator. Other image sources, such as mirrors ormonitors of any kind, may also be employed as the image source. In thesecases, too, it is advantageous for the camera size to be specified, intwo dimensions, i.e. in the length and width, by the size of the imagesource with regard to these dimensions.

In particular, the mirror arrangement comprises a first mirrorconfigured to reflect any light emitted by the planar image source. Themirror arrangement further comprises a second mirror arranged to againreflect the light reflected by the first mirror. The first and secondmirrors are spaced apart from each other and are arranged in parallelwith or at an acute angle relative to each other.

In this manner, any radiation, such as X-radiation, which is notdeflected by the mirrors impinges on a mirror and is already attenuatedby the mirror without requiring further measures for shielding off.

For example, the mirror arrangement is configured to shield at leastsome X-radiation, which penetrates a scintillator layer, from thedetector, such that X-radiation passing through the scintillator layercannot arrive directly at the detector, but passes through the firstmirror and the second mirror and is at least weakened in the process,such that the detector is protected from X-radiation by the mirrorarrangement. Preferably, the mirror arrangement is configured to shieldat least 30% (e.g. for hard radiation) or advantageously even 80% (e.g.for soft radiation) of the radiation impinging on the mirror arrangementfrom the sensitive optical detector. Depending on the energy of theX-radiation, shielding should be performed to a greater or lesserdegree. Very hard, i.e. high-energy, radiation of a high frequency isless critical to the optical detector (detector optics andphotosensitive sensor), due to the low absorption, than is softradiation, i.e. radiation having lower energy and shorter wavelength.However, softer radiation is easier to shield off, so that an optimumdesign of the mirror arrangement may be found for each case ofapplication (in particular with regard to frequency). Sometimes, even amirror glass, perhaps comprising a relatively large thickness, and ashielding glass at the optics of the detector may suffice, and in othercases, classic shielding materials such as lead or bismuth materials mayindeed be used.

For applications where the X-radiation energy is not particularlystrong, this may already suffice to ensure that a sensitive detectorwill not receive too large a radiation dose. However, if relatively highradiation energy is used, the mirrors may be specifically configured toprovide a shield for X-rays, shielding materials for X-rays being leador tungsten, for example.

Unlike mirrors which may consist of a coated pane of glass, such“shielded-off” mirrors are such mirrors which may consist of a coateddisk (e.g. pane of glass) which is applied to a shielding material whichdiffers from the disk, or pane, and has a higher X-ray shielding effectthan the disk or pane. Alternatively, such a shielded-off mirror mayalso be a mirror wherein a surface of a material, which already shieldswell, is processed so as to act as an optical mirror. Such awell-shielding material is lead or tungsten or any other material havinga better X-ray shielding property than glass, when two disks of materialwhich have the same thickness are compared.

Sandwich-like inclusion of the mirror arrangement between the detectorand the planar image source results in a system which is compact, simpleto manufacture and, thus, efficient even in terms of production cost.The entire arrangement of the X-ray camera may therefore be designed,using the scintillator and the light emitted by the scintillator, suchthat a compact object is obtained, the size of which scales with thesize of the scintillator and, therefore, with the inherent qualityfeature.

The concept of using at least two mirrors within the mirror arrangementis particularly suitable for subregion-wise imaging of a scintillator,which is may be used when the scintillator is particularly large.

Subdivision of the scintillator into subregions, which are deflected byvarious mirrors and are directed to a specific detector camera, isreadily achieved by simply adding further pairs of mirrors. Simplyjoining together further pairs of mirrors enables having a cameraconcept for various scintillator sizes which may be readily translated,without any need for entirely new designs, to larger and smallerscintillators. The modular structure may be advantageously used simplyin that further pairs of mirrors and, thus, corresponding furtherdetector cameras are employed. In the direction, which is orthogonalthereto, of the two-dimensional scintillator, a simple modular structureis also possible, since detector cameras may readily be arranged side byside with each other so as to detect subregions of the deflectingmirrors. A large scintillator screen may therefore be imaged using anarray of detector cameras, wherein each detector camera finally images asubregion of the scintillator screen. Alternatively or additionally, itis also possible to arrange several relatively small mirrors side byside with one another, so that a detector will fully record one smallmirror, but each small mirror deflects only the light radiation of asubregion of the image source. It is also possible to arrange severalrelatively large mirrors side by side with one another, so that adetector camera will detect, for example, only a subregion of a mirror,and such that a mirror nevertheless does not deflect the light of theentire image source, but only light of a subregion which, however, islarger than the subregion which will be finally detected by a detectorcamera.

Preferably, two mirrors are arranged back to back, it being possible forthe two mirrors to already consist of a material which shields well, aswas described above, or the mirrors being disposed on the front side andback side, respectively, of such an absorbing material, so that, as aresult, the absorbing material differs from a mirror support materialsuch as pane of glass of a classic mirror, for example.

These individual images may then be composed using a computer, it beingadvantageous to ensure that the subregions will overlap so as to preventany image losses, that is non-picked-up locations of the scintillatorscreen, from occurring even with relatively small misalignments.

The present invention therefore enables subdividing the scintillatorscreen into basically any number of optical cameras in a simple manner.Without changing the structural depth, a scintillator area having anysize may be imaged to a correspondingly large number of optical cameras.In addition, the size, or the dimensions, of the X-ray camera is verysimilar, with regard to two dimensions, to the size of the scintillatorscreen with regard to these two dimensions, which cannot be achieved bylaterally arranging the optical cameras.

In advantageous embodiments, a specific area of the scintillator screenis imaged onto each camera, respectively, the areas only slightlyoverlapping so as to be able to represent, following correspondingcorrection, the entire scintillator area.

The present invention therefore enables a modular architecture, so thatany size and shape of a scintillator may be imaged by adding furthermodules in the form of further pairs of mirrors or in the form ofdetector cameras which detect different regions of one and the samedeflection mirror. In this manner, an X-ray camera may be built which isadapted to the size and shape of the device under test on which the sizeand shape of the scintillator screen eventually depend.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be detailed subsequentlyreferring to the appended drawings, in which:

FIG. 1 a shows a basic representation of the basic arrangement of theindividual elements of the inventive apparatus;

FIG. 1 b shows a schematic three-dimensional view of a “sandwich”consisting of a scintillator, a mirror arrangement and a detector;

FIG. 2 is a side view of a vertical arrangement having two parallelmirrors, it being possible for any number of cameras to be arranged inrows perpendicularly to the drawing plane;

FIG. 3 is a side view of a 2×2 parallel mirror arrangement, it beingpossible again for any number of cameras to be arranged in rowsperpendicularly to the drawing plane;

FIG. 4 is a side view of a vertical arrangement having two parallelmirrors and diaphragms/shields for reducing scattered X-radiation and/orthe aperture angle for direct radiation, it being possible again for anynumber of cameras to be arranged in rows perpendicularly to the drawingplane;

FIG. 5 shows a basic arrangement of an X-ray camera having a sensorlaterally to the scintillator; and

FIG. 6 shows a known arrangement of an X-ray camera having a V-shapedmirror arrangement and laterally mounted light sensors.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 a shows a schematic representation of the apparatus for detectingan image. The apparatus for detecting an image comprises a planar imagesource 100 and a mirror arrangement 110 for deflecting radiation whichmay be generated by the image source 100. The light radiation generatedby the planar image source 100 is schematically depicted at 102. Thus,the mirror arrangement 110 receives the light radiation 102 at the inputside, and outputs deflected light radiation 119 which will impinge on adetector 120. The detector is configured to receive the light, or theradiation, 119 deflected by the mirror arrangement 110. At the outputside, the detector 120 may be connected to a computer 130, which outputsthe image generated by the planar image source 100 via a monitor or aprinter in the form of a printed copy (hard copy) or as a file (softcopy). Therefore, the device 140 may be a memory, a monitor, a printeror, e.g., a communication interface so as to transmit the image to aremotely arranged printer or monitor, so that it will eventually beoutput there. Alternatively or additionally, composition of theindividual images may be followed by an automatic evaluation beingperformed and by the evaluation result being output. In addition,evaluation may also take place in the form of a computer tomography,i.e. in that a presentation is generated on the basis of sectionalimages.

With reference to FIG. 1 b, a specific embodiment of the mirrorarrangement 110 shall be addressed below. In particular, the mirrorarrangement 110 comprises two spaced-apart mirrors, a first mirror 111being arranged, in particular, to reflect the light, or the radiation,102 coming from the planar image source 100. In particular, the firstmirror 111 is arranged such that it will not directly reflect back thelight, but reflect it to a second mirror 112, the second mirror 112being arranged to again reflect the light reflected by the first mirror.

As is shown in FIG. 1 b, the first and second mirrors 111, 112 arespaced apart from each other and are arranged in parallel with or at anacute angle relative to each other which is smaller than 90°. Thisensures that the light reflected by the second mirror 112 is reflectedin the direction of the detector 120. For example, the mirrorarrangement 110 may also have further mirrors arranged therein which arenot shown in FIG. 1 b, but which will be addressed later on withreference to FIG. 3, for example. The mirror arrangement is such thatthe light reflected by the second mirror 112 has at least one componentwhich is directed along the direction from the screen 100 to thedetector 120. Therefore, if the mirror 112 were tilted slightly furtherdownward, the light reflected by the second mirror 112 would have adirection, for example, as is drawn in at 113. The radiation 113therefore has a component which exists in parallel with the vector 102,and additionally has a component which is directed downward in FIG. 1 b.To detect such a radiation, the detector 120 in FIG. 1 b would have tobe arranged slightly further down.

Similarly, the second mirror 112 could be slightly tilted upward ascompared to the parallel arrangement of FIG. 1 b, so that any radiationemitted by the second mirror 112 would be directed upward in relation tothe vector 102. In this case, the detector 120 could also be arrangedslightly further up so as to detect this radiation as well. The twomirrors 111, 112 therefore need not necessarily be arranged in parallel,but should be arranged at least such that an acute angle, i.e. of lessthan 90°, is present between the two mirrors so that the radiationoutput by the second mirror 112 has at least one component in thedirection of the vector 102, which is the normal vector on the planarimage source 100. The larger the component, which is parallel to thevector 102, of the radiation output by the second mirror 112, the morecompact the configuration of the entire apparatus, including the planarimage source 100 and the detector, may be, an angle of between 0 and 80°between the two mirrors being specifically advantageous.

The two mirrors 111, 112 have the advantage that they cover a“line-of-sight connection” between the detector 120 and the planar imagesource 100, but that nevertheless the light directed from the planarimage source 100 to the detector 120 is detectable, i.e. is not shadedby the two mirrors 111, 112.

In particular when the planar image source 100 is a scintillator whichis excited by X-radiation 99 on that side which in FIG. 1 b is its rearside, what is achieved by this is that the detector 120 is protectedfrom the X-rays 99 despite the fact that it is arranged within the lightpath. X-rays which pass through the scintillator 100 cannot arrive atthe detector directly, but penetrates the two mirrors 111, 112. Intypical arrangements, the mirrors 111, 112 are reflective only for suchlight rays emitted by the scintillator 102 which are within the visiblerange. However, the X-rays 99 are not reflected, but scattered orabsorbed by the mirrors 111, 112. Thus, the ratio of the intensity ofthe light radiation 115 to the X-radiation is larger between the mirrorarrangement 110 and the detector 120 than between the mirror arrangement110 and the planar image source 100. This is due to the fact that theX-radiation is attenuated to a greater extent by the mirror arrangementthan is the visible (useful) radiation. The detector 120, which, e.g.,is a detector on the basis of a semiconductor chip such as a detectorhaving a CCD camera, is therefore protected by the mirror arrangement110 from the X-radiation 99 which is used for exciting the scintillator100, so that same will emit the useful radiation 102. Generally,therefore, a radiation having a short wavelength will impinge on thescintillator 100 from the rear side, and the scintillator 100 will emita radiation 102 having one or several wavelengths which are longer, by afactor of at least 10, than the wavelength of the radiation behind thescintillator, the mirrors 111, 112 having an attenuating effect on theshort-wave radiation, and having a reflecting effect on the longer-waveradiation, or having a more intense reflecting effect on the longer-waveradiation than on the short-wave radiation.

The concept depicted in FIGS. 1 a and 1 b of an apparatus for detectingan image generated by a planar image source, such as a scintillatorscreen, for example, may advantageously be employed for dividing up thescintillator screen into any number of optical cameras. The advantage ofthis concept consists in that a scintillator area of any size may besubdivided into a correspondingly large number of optical cameraswithout changing the structural depth, and in that the dimensions of theX-ray camera will nevertheless correspond, in terms of length and width,to the size of the scintillator screen in terms of length and width,whereas this has not been achieved in conventional technology, since inconventional technology, the optical cameras have been arrangedlaterally in relation to the scintillator screen. In the presentinvention, a specific area of the scintillator is advantageously imagedonto each camera, respectively, the areas slightly overlapping so as tobe able to depict, following corresponding correction, the entirescintillator area, it being possible for this correction and thecomposition of the individual images of the individual detector camerasto take place within the computer 130 of FIG. 1 a. In this manner, amodular architecture is enabled wherein, in principle, any size andshape of the scintillator may be imaged by adding further modules. Inthis manner, an X-ray camera may be built which is adapted to the sizeand shape of the device under test, i.e. of the object X-rayed by theX-radiation 99.

FIG. 1 b shows an arrangement comprising two mirrors 111, 112, it alsobeing possible to arrange one or, e.g., more cameras within the detectorin the y direction so as to have a row of cameras. Then each individualcamera images a subregion of the light 115 output by the mirror 112,this subregion being a subregion in the y direction in FIG. 1 b.

FIG. 2 shows an alternative arrangement wherein several pairs of mirrorsare arranged in the z direction, several sensors also being arranged inthe z direction, so as to detect the light reflected by the secondmirror of a pair of mirrors in each case. In particular, FIG. 2 showsdashed lines shown at 501 and indicating the region 502 of thescintillator in the z direction, which is detected by the first pair ofmirrors 111, 112 and is directed to a first detector camera 121. Asecond subregion in the z direction, designated by 505, is detected by asecond pair of mirrors, which comprises a third mirror 116 a and afourth mirror 116 b, and is imaged to a second sensor 122. The imaging“process” is indicated by the continuous lines 504. A fifth mirror 117 aand a sixth mirror 117 b form a third pair of mirrors, which images aregion 507 of the scintillator in the z direction, the imaging processbeing indicated by the dash-dotted lines 506 so as to image this region507 to the third sensor, or the third sensor camera, 123. Thus, thedetector 120 comprises three detector cameras 121, 122, 123, in whichcontext it should be noted that in the y direction, it is not absolutelynecessary for there to be one single detector camera, but that typicallyseveral detector cameras may be present, such that the detector 120comprises an array of detector cameras, the individual images of thedetector cameras being composed by the computer 130 to form an overallimage.

In addition, FIG. 2 indicates that the regions of the scintillator whichare imaged to a camera by a pair of mirrors, or which are imaged to arow of cameras, respectively, will slightly overlap. The overlap resultsfrom the overlap of the region 502 with the region 505 and from theoverlap of the region 505 with the region 507.

In FIG. 2, all six mirrors are arranged in parallel with one another,the mirror 116 a being arranged on the rear side of the mirror 112. Thesame applies to the fourth mirror 116 b and the fifth mirror 117 a.Again, both mirrors are arranged such that their rear sides abut on eachother. A specific implementation for the element having the secondmirror 112 and the third mirror 116 a consists in that a support isprovided which is mirrored on its top surface so as to form the mirror112, and which is also mirrored on its bottom surface so as to form themirror 116 a. This mirroring may be achieved by a specific surfacetreatment or surface coating of the support. The support for the fourthmirror 116 b and for the fifth mirror 117 a may be implemented in asimilar manner, i.e. such that the top and bottom surfaces are treatedor coated accordingly so as to implement the mirrors 116 b, 117 a.

In accordance with the invention, in the embodiment depicted in FIG. 2the scintillator screen is imaged to several optical cameras in such amanner that only the visible light emanating from the scintillator willimpinge on the optical cameras, and that any X-radiation which may passthrough the scintillator will not be able to cause any radiation damagein the sensors 121, 122, 123. For this purpose, two mirrors 111, 112,and 116 a, 116 b, and 117 a, 117 b, respectively, are arranged inparallel with one another within the light path of each camera, as isshown in FIG. 2, in such a manner that the visible light emanating froma subarea of the scintillator reaches the camera, but such that nodirect “open” path to the camera exists for X-radiation. Rather, thedirect X-radiation crosses, on its way to the camera, at least one ofthe mirrors, or, as will be set forth below, double-mirror arrangements.For scattered X-radiation, the conditions are different, but scatteredX-radiation is weaker than direct radiation.

To intensify the weakening of the X-radiation on its way through themirrors even more, it is advantageous to provide the mirrors with asufficiently thick absorber layer, such as lead, for example, on theirrear sides in order to effectively weaken the X-radiation. As may beseen from FIG. 2, a double mirror, or a support mirrored on both sidesmay be used instead of an individual mirror for such camera arrangementswhich are not located at the edge, in order to periodically continue thearrangement. In one embodiment, this support is formed from a materialhaving a high level of absorptive power for X-radiation, and havingsufficient mechanical stability. Such a material is tungsten or lead,for example. Alternatively, an absorber layer which is designedaccordingly and is made of lead, for example, may be arranged betweenthe two mirrors of the double-mirror arrangement, i.e. between themirrors 112, 116 a, and 116 b and 117 a, respectively.

To have increased protection from scattered radiation, it is alsoadvantageous to shield the detector arrangement 120, as is shown at 124in FIG. 2. The shield 124 may be a lead shield or any other shield whichattenuates X-rays. Only regions 125 a, 125 b, 125 c, at which visibleradiation may enter into the shield 124, are open, or are transparent tooptical radiation, whereas transparence to optical radiation outsidethese regions is not necessary and is not implemented, since X-rayshields may be implemented at low cost when they do not have to beoptically transparent.

Depending on the beam direction, i.e. on the position of the X-raysource in relation to the midperpendicular of the scintillator, however,with the double-mirror arrangement there are, for X-radiation, directopen paths to an optical camera. Specifically, if the X-radiation isarranged, e.g., at a position P510, X-rays exiting at the position P510may enter into the sensor 123 without these X-rays having beenattenuated by a double-mirror arrangement. To prevent the sensor 123from being damaged, it is advantageous to avoid this direct path. Onemanner to avoid this direct path consists in not allowing anyarrangements to exist between the X-ray source and the scintillator, butin allowing only arrangements of the X-ray source behind a centralregion of the scintillator, which region may be the region 505, forexample.

However, to have a more variable possibility of arranging the X-raysource in relation to the scintillator, and also to be safer fromscattered radiation—the scattered radiation being considerably lessintense than the X-ray intensity existing between the scintillator andthe mirror arrangement—the embodiment shown in FIG. 2 provides theshield 124 which is interrupted (125 a, 125 b, 125 c) only where this isuseful for optical imaging. At the places where the shield housing isinterrupted for optical radiation, shielding from X-rays is additionallyperformed in that, advantageously, a specific glass is arranged withinthe optical light path which is transparent to visible light, butstrongly absorbs X-radiation. Such a glass is lead glass, for example.

A further possibility of shielding consists in that the optics of thesensor cameras 121, 122, 123 are manufactured from a correspondingspecial glass, such as lead glass, for example, so that the imagingoptics will absorb X-radiation, but will be transparent to visiblelight. Depending on the implementation, this approach may bedisadvantageous, however, since currently available special glass havinga high level of X-ray absorptive power also absorbs some visible light.However, if the intensities of the visible light emitted by thescintillator are sufficiently large, the radiation detected by thedetector cameras will be sufficient to generate an image having asufficient signal/noise ratio.

A further implementation for reducing X-radiation in accordance with thedouble-mirror arrangement is shown in FIG. 3. A further pair of mirrors118 a, 118 b is arranged, the first mirror 118 a of the further pair ofmirrors being arranged to deflect the light reflected by the secondmirror 112 of the mirror arrangement, and the second mirror 118 b of thefurther pair of mirrors being arranged to deflect the light, which isdeflected by the first mirror 118 a of the further pair of mirrors, inthe direction of the detector 121. Thus, one or several furtherdouble-mirror arrangements, not shown in FIG. 3, are placed into theoptical light path. As a result, for random arrangements of the X-raysource, with regard to the camera, there is not longer any direct pathfrom the sensor to an X-ray source arranged before the scintillatorscreen.

This is due to the fact that the two mirror arrangements cover directpaths from the X-ray source located behind the scintillator screen tothe active detector regions, which is achieved, for example, in that thefirst mirror 111 and the first mirror 118 a of the further pair ofmirrors contact each other, and that the second mirror 112 and thesecond mirror 118 b of the further mirror arrangement also contact eachother. Even if the two mirrors do not contact each other, a shield maybe arranged within the region where the mirrors are not required forreflection, such that no direct path is possible from an X-ray sourcelocated behind the scintillator 100 without any intermediate shield tothe sensor 121. As in FIG. 2, the arrangement shown in FIG. 3 may becontinued as desired in the upward direction, i.e. in the z direction,as well as in the y direction, i.e. in the direction vertical to thedrawing plane. Since the X-radiation may now reach a camera onlyfollowing multiple scattering processes, its intensity is considerablyreduced in this arrangement as compared to a simple double-mirrorarrangement. Depending on the implementation, the further shieldingmeasures as were described in connection with FIG. 2 and which are notabsolutely necessary in this arrangement may also be additionallyimplemented.

A further embodiment for reducing X-radiation is shown in FIG. 4.Shields 520, or diaphragms 522, are provided before the first mirrorand/or behind the second mirror. In particular, shields 520 are providedon the mirror side facing the scintillator 100, and/or diaphragms 522are provided on the mirror side facing the detector 120. Preferably, theshields 520 and the diaphragms 522 are made of a material which absorbsX-rays, such as lead. An alternative material to lead may also beprovided as long as it has an X-ray absorbing effect, such as tungsten,for example. FIG. 4 shows the arrangement of the shields and/ordiaphragms with regard to the light paths 501, 504, 506. It may be seenthat the light paths 501, 504, 506 are not impaired by the shields 520and the diaphragms 522. Some of the scattered X-radiation which mightget from the diaphragms to the first mirror is absorbed in this manner.In addition, the range of angles from which X-radiation would directlyimpinge on a camera is reduced. For example, the direct path of theX-radiation source at the point P510 to the lower sensor 123 iseffectively interrupted by the second shield 520.

It shall be noted that the specifically shielded arrangement shown inFIG. 4 which comprises the shields 520 and the diaphragms 522 (it beingpossible, in specific arrangements, for either diaphragms 522 or shields520 to suffice) is advantageous with regard to a compact design. Thereason for this is that in this case, there is a large region whereinthe X-ray source may be arranged in relation to the scintillator 100without there being a direct open path to one or more optical cameras.In particular, the arrangement shown in FIG. 4 will be sufficient whenthe X-ray source is arranged at a sufficiently large distance along themidperpendicular of the scintillator screen, which is typical of mosttechnical applications. If, in the embodiment shown in FIG. 4, a specialglass may additionally be used for absorbing the X-rays in the regions125 a, 125 b, 125 c or in the optics of the sensor cameras, however, theabsorption effected by this special glass may be disadvantageous ascompared to the arrangement depicted in FIG. 3, which may dispense withsuch a special glass. Specifically, many special glasses have thedisadvantage that over time they develop an increased level ofattenuation since they exhibit a “browning effect” due to theX-radiation.

This will be the case, in particular, when the reflection losses causedby the double-mirror arrangement are smaller than the losses caused bythe special glass, and when the structural depth, which is larger inFIG. 3, does not prohibit utilization of such a camera. Therefore, onemay have to weigh up the optical absorption of the arrangement shown inFIG. 4, including special glass for absorbing the X-radiation, and thereflection losses of a further double-mirror arrangement in accordancewith FIG. 3. With a very high radiation energy, an arrangement of FIG. 3may therefore be advantageous.

In an inventive method of detecting an image, radiation is initiallyemitted by a planar image source, which radiation is then deflectedwithin the mirror arrangement and detected within the detector, the twomirrors 111, 112 being utilized in the deflection, and these mirrorsbeing spaced apart such that they are parallel with each other or forman angle of less than 90° between them. For manufacturing such anapparatus, an image source, a detector and a mirror arrangement aretherefore arranged such that they face one another, the two mirrors 111,112 being arranged in parallel with each other or arranged at an angleof less than 90° between them, so that the light 115 reflected by thesecond mirror 112 will be parallel to the light 102 reflected by theplanar image source, or will have at least one component which extendsin parallel with the direction designated by the vector 102.

The computer 130 is configured to compose the individual images into anoverall image. This composing process advantageously takes placefollowing an analog/digital conversion. In addition it is advantageousto perform a corresponding correction on the basis of the overlapregions, these overlap regions existing both in the z direction, as isshown by way of example in FIG. 2, and in the y direction if severalsensors image a mirror, even though this overlap region is not drawn inin FIG. 2. In addition, the computer may be configured to correctoptical distortions or other artifacts which are detected duringcalibration of the apparatus and are then computationally compensatedfor during operation.

While this invention has been described in terms of several embodiments,there are alterations, permutations, and equivalents which fall withinthe scope of this invention. It should also be noted that there are manyalternative ways of implementing the methods and compositions of thepresent invention. It is therefore intended that the following appendedclaims be interpreted as including all such alterations, permutationsand equivalents as fall within the true spirit and scope of the presentinvention.

1-23. (canceled)
 24. An apparatus for detecting an image, comprising: animage source comprising a scintillator layer which is excitable by anX-radiation for emitting the radiation; a mirror arrangement fordeflecting radiation which may be generated by the image source; and adetector for receiving radiation deflected by the mirror arrangement,the detector being arranged within a light path of the X-radiation, themirror arrangement comprising: a first mirror arranged to reflect theradiation generated by the image source; a second mirror arranged toreflect radiation reflected by the first mirror, the first mirror andthe second mirror being spaced apart from one another and being parallelto one another or forming an angle of less than 90° between them, andthe mirror arrangement being configured to shield at least someX-radiation which penetrates the scintillator layer from the detectorsuch that X-radiation which passes through the scintillator layer cannotarrive directly at the detector, but passes through the first mirror andthe second mirror and is at least weakened in the process, such that thedetector is protected from X-radiation by the mirror arrangement. 25.The apparatus as claimed in claim 24, wherein the mirror arrangementfurther comprises: a third mirror and a fourth mirror, the first mirrorbeing arranged to reflect only such radiation to a sensitive detectorregion which comes from a first subregion of the image source, the thirdmirror being arranged to reflect only such radiation to a sensitivedetector region which comes from a second subregion of the image source,the first subregion differing from the second subregion, the fourthmirror being arranged to reflect radiation reflected by the thirdmirror, the third mirror being arranged on a rear side of the secondmirror, and an X-ray absorber material being arranged between the secondmirror and the third mirror, or the second mirror and the third mirrorbeing configured on different sides of a support material absorbingX-rays.
 26. The apparatus as claimed in claim 24, wherein the detectorcomprises several detector cameras, wherein the mirror arrangementcomprises several pairs of mirrors, each pair of mirrors comprising adetector camera each comprising a sensitive detector region associatedwith it, and the detector further being coupled to a computer configuredto join together images recorded by the detector cameras so as toacquire the image.
 27. The apparatus as claimed in claim 24, wherein thefirst mirror and the second mirror are arranged such that a direction ofthe radiation reflected by the second mirror to the radiation impingingon the first mirror comprises an angle of between 0 and 80°.
 28. Theapparatus as claimed in claim 24, wherein the first mirror and thesecond mirror are arranged such that at least one mirror is arranged ona shortest connecting line between the detector and the image source, sothat a radiation which propagates in the direction of the shortestconnecting line impinges on the at least one mirror.
 29. The apparatusas claimed in claim 24, wherein the image source comprises ascintillator layer configured to generate the radiation in response toincidence of X-rays, the radiation comprising one or more wavelengthswhich are detectable by the detector.
 30. The apparatus as claimed inclaim 24, wherein the first mirror and the second mirror are arrangedsuch that the radiation deflected by the mirror arrangement is deflectedin a direction which is parallel to a normal to surface of the imagesource, or which forms an angle of less than 80° with the normal tosurface.
 31. The apparatus as claimed in claim 26, further comprising: afifth mirror and a sixth mirror, the fifth mirror and the sixth mirrorbeing configured to image only a third subregion of the image source toa sensor.
 32. The apparatus as claimed in claim 31, wherein the fifthmirror is arranged on a rear side of the fourth mirror, an X-rayabsorber material being arranged between the fifth mirror and the fourthmirror, or the fifth mirror and the fourth mirror being configured ondifferent sides of a support material absorbing X-rays.
 33. Theapparatus as claimed in claim 24, wherein the detector is arranged, inthe direction of radiation, opposite the image source.
 34. The apparatusas claimed in claim 24, wherein the mirror arrangement comprises severalpairs of mirrors, each pair of mirrors comprising a detector cameraassociated with it, the detector further being coupled to a computerconfigured to join together images recorded by the detector cameras soas to acquire the image.
 35. The apparatus as claimed in claim 24,wherein a pair of mirrors comprises several detector cameras associatedwith it, so that there is a detector camera array which comprises anumber of array columns equal to the number of detectors associated witha pair of mirrors and wherein a number of array rows is equal to anumber of pairs of mirrors, wherein the number of pairs of mirrors canbe 1 or larger than 1, the detector being coupled to a computerconfigured to join together images recorded by the detector cameras soas to acquire the image.
 36. The apparatus as claimed in claim 24,wherein the mirror arrangement further comprises: a further pair ofmirrors, wherein a first mirror of the further pair of mirrors isarranged to deflect light reflected by the second mirror, and whereinanother, second mirror is arranged to deflect light, which is deflectedby the one mirror of the further pair of mirrors, in the direction ofthe detector.
 37. The apparatus as claimed in claim 24, accommodatedwithin a housing, the size of which, perpendicular to a normal of theimage source, is smaller than 1.2 times a corresponding size of theimage source.
 38. The apparatus as claimed in claim 24, wherein themirror arrangement is configured to absorb or to scatter at least someof the impinging X-radiation, so that the X-radiation is attenuated inintensity by at least 20% by the mirror arrangement.
 39. The apparatusas claimed in claim 24, wherein the first mirror and the second mirrorcomprise an X-ray absorber layer.
 40. The apparatus as claimed in claim24, wherein the detector is surrounded by an X-ray shield configured toshield the detector where the radiation deflected by the mirrorarrangement does not enter into the detector.
 41. The apparatus asclaimed in claim 24, wherein a location of the detector at which thedeflected radiation enters comprises a shielding glass which absorbsX-rays to a greater extent than the deflected radiation.
 42. Theapparatus as claimed in claim 24, wherein the detector comprises adetector camera which comprises an optics arrangement configured toabsorb X-rays to a greater extent than the deflected radiation.
 43. Theapparatus as claimed in claim 24, wherein the mirror arrangementcomprises X-ray absorbing diaphragms in locations which are not imagedby a detector camera, or which are imaged by the detector camera but areeliminated during image post-processing.
 44. The apparatus as claimed inclaim 24, wherein the mirror arrangement comprises X-ray absorbingshields in locations which do not lie within a detected light path fromthe image source to the first mirror, or which lie within a detectedlight path from the light source to the first mirror and are eliminatedduring subsequent image processing.
 45. A method of detecting an image,comprising: emitting a radiation which represents an image; deflectingthe radiation so as to acquire deflected radiation; and detecting thedeflected radiation so as to acquire the image, during deflecting, theradiation being reflected by a first mirror, and the radiation reflectedby the first mirror being deflected by a second mirror, the first mirrorand the second mirror being spaced apart from each other and beingparallel to each other or forming an angle of less than 90° betweenthem, during emitting, a scintillator layer being excited by X-radiationso as to generate the emitted radiation, and during deflecting,shielding of the X-radiation from the detector being conducted such thatX-radiation passing through the scintillator layer cannot arrive at thedetector directly, but passes through the first mirror and the secondmirror and is at least weakened in the process, such that the detectoris protected from X-radiation by the mirror arrangement.
 46. A method ofmanufacturing an apparatus comprising an image source comprising ascintillator layer which is excitable by an X-radiation for emitting theradiation, a mirror arrangement for deflecting radiation which may begenerated by the image source, and a detector for receiving radiationdeflected by the mirror arrangement, the detector being arranged withina light path of the X-radiation, the method comprising: arranging afirst mirror to reflect radiation emitted by the image source; andarranging a second mirror to reflect radiation reflected by the firstmirror, and during arranging the first mirror and the second mirror, thetwo mirrors being arranged such that they are spaced apart from eachother and are parallel to each other or form an angle of less than 90°between them, and the mirror arrangement being configured to shield atleast some X-radiation which penetrates the scintillator layer from thedetector such that X-radiation which passes through the scintillatorlayer cannot arrive directly at the detector, but passes through thefirst mirror and the second mirror and is at least weakened in theprocess, such that the detector is protected from X-radiation by themirror arrangement.